This invention relates to an amplifier for use in conjunction with electric guitars.
Amplifiers for guitars are well known and in use, and they continue to evolve. Originally, and for many years, guitar amplifiers were simple circuits with a single sound and a single volume control. In the late 1970s, the inventor herein began an intense development of the art by introducing the first amplifier with dual mode performance. As set forth in U.S. Pat. No. 4,211,893, this development added a separate high-gain mode of amplification to generate musically desirable harmonics for enhancing single note playing, also known as lead playing. Because of its high gain, the new lead mode was provided with one or more separate attenuators for gain adjustment as well as an attenuator for setting the playing loudness. The dual mode amplifier also included a traditional mode with standard gain for undistorted chordal playing and this mode included its own attenuator for adjusting loudness. Thus, the playing level of either lead or rhythm mode could be set independently.
For many years, the lead enhancement mode was used more or less exclusively for soloing while the traditional rhythm mode was used for foundational playing. Thus, the separate level controls for the individual modes enabled the player to set the lead mode slightly louder for featuring a solo. Over the years, musical styles have changed, blurring the once clear distinction between lead and rhythm playing. Currently, many musical styles may incorporate various amounts of amplifier distortion for either rhythm or lead playing. A guitarist may wish to xe2x80x9cstep forwardxe2x80x9d in the band""s mix for a spotlight feature in any mode, including modes used primarily for background playing. Thus, the ability to boost the volume level without switching to a different mode provides a unique and valuable capability. This ability is not presently available in prior art amplifiers for use in conjunction with a guitar.
In accordance with the present invention, the above-described desirable capability is provided and provides an alternate level for overall audio output. The alternate output level may be preset by providing a dedicated attenuator control which is accessed by a footswitch or other remote device, preferably operable by the player desiring the alternate output level. Operating independently from individual channel controls, the alternate output feature enables the guitarist to attain solo volume in any mode at any time during his or her performance.
Briefly, the above is accomplished by introducing into the amplifier circuit a volume or loudness level shifting circuit which is switch operated. The switch is preferably remotely controllable, such as, but not limited to a footswitch operated, preferably by the player desiring the level shift. The level shifting circuit provides, in one state, normal adjustable attenuation and, in a second state, a fixed attenuation level which is preferably preset. In accordance with another embodiment, the signal is passed through a coupling capacitor to remove any d-c signal on the line with the output from the level shifter passing through a variable resistor which is connected to reference voltage (ground) via a variable resistor in one state and directly to reference voltage in the second state, the state being determined by the position of the switch. In accordance with a further embodiment, the signal is passed through a coupling capacitor as in the first embodiment with the signal then being passed to reference voltage through a pair of variable resistors. The wipers on the variable resistors are connected through a switch to the level shifter output, the switch being connected to only one of the wipers. The switch position is remotely controlled as discussed above.